Electronic systems, such as microprocessor based computers, typically operate on data that is stored in electronic form in a memory device. The memory device stores the data at specified voltage levels in an array of cells. The voltage levels represent that the data is either a logical "1" or a "0." In dynamic random access memory (DRAM) devices, for example, the cells store the data as a charge on a capacitor. When the data is read from the memory device, the device checks the charge on the capacitor using sense amplifiers that detect small differences in charge on these capacitors so as to produce a "1" or a "0" output based on the stored charge.
As the size of memory devices decreases, the capacitor in each cell occupies a smaller surface area of the semiconductor substrate. These smaller capacitors cannot store as much charge because the storage capacity of a typical capacitor is proportional to the size of its storage electrodes. Typically, the area of the storage electrode is approximately equal to the surface area of the substrate dedicated to the capacitor. Unfortunately, at some point, the size of the smaller capacitors interferes with the ability of the sense amplifiers to differentiate between charge on the capacitors due to noise and the charge due to data stored in the cell. This can lead to errors in the output of a memory device making the memory device useless in the electronic system.
Designers have experimented with various techniques for producing capacitors that can store more charge while using less surface area of the semiconductor substrate. In these devices, designers have used texturization, stacked V-shaped plates and other shaped plates to increase the size of the electrode without increasing the surface area of the substrate used for the capacitors. Unfortunately, there are drawbacks with these techniques. For example, the techniques add a number of mask steps to the traditional process flow thus increasing the complexity of the process and the chance for errors to creep into the final product.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a capacitor for use in, for example, a memory device with increased storage capacity without adding mask steps that disrupt and complicate the traditional process flow.